Fabrication of chitosan and calcium carbonate bio-crystals for humidity sensor prepared from annealed shrimp shells and eggshells

Abstract

We reported the catalyst-free humidity sensor prepared from shrimp shells and eggshells. The annealed shrimp shells and eggshells were ground to powder and mixed together at various ratios. The samples were characterized and investigated by X-ray diffraction technique (XRD), Scanning electron microscope (SEM) and humidity sensing measurements. As a result, XRD patterns of shrimp shells and eggshells show chitosan and CaCO3 structures, respectively. Their SEM images indicate massive agglomeration. Moreover, the humidity sensor demonstrates the highest sensitivity of shrimp shells and eggshells at the ratio of 1:1 for 4.81 at 85%RH. The resistance and relative humidity relationship indicates non-linear inverse behavior. However, the resistance of the samples decreases at higher relative humidity.